100R — solar cooking experiment

solar cooking experiment<br>2023.11.30<br>Salish Sea

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2026.06.11

A summer of solar cooking

In the spring of 2023 we learned about solar evacuated tube cooking(See page for more details about solar tubes), an efficient way of preparing food with the sun. We spent our first summer experimenting with such a cooker, in which we learned to plan our meals with the weather.

A note on local conditions: We tested the solar cooker while in the Salish Sea, where summer daytime temperatures range from 12-32°C. We also experimented in 5°C temperatures.

We prioritized the use of the solar cooker when preparing foods with long cooking times, like brown rice, beans, potatoes, seitan, cake and bread. It would have been possible to prepare all parts of a meal with the solar cooker, but we didn't want it to become a ball and chain, keeping us onboard all day. Solar cooking isn't terribly demanding, but it requires some attention.

On days of full sun , we could cook one full meal. In the morning(0900-1000) we'd prepare chickpeas, then bake bread in the afternoon(anytime between 1300-1700).

On days of Sun with overcast periods , we'd cook food with quick-cooking times like white rice, brown lentils, potatoes or seitan.

On very rainy/heavily overcast days, solar cooking was not possible.

If planning to cook foods with long wait times, such as bread(needs time to rise), or beans(needs soaking), we would check the forecast to make sure the next day's weather would permit it. If there was sun, we'd pre-soak the beans or pre-mix the dough before bed so everything would be ready to cook come morning.

The closer the sun gets to the horizon, the harder it is to find a good angle for the cooker, which is why it is better to prepare meals in the morning or in the early afternoon.

We liked to place the cooker on the bow, on the space above the anchor locker just ahead of the forward hatch.

That space is relatively flat, which keeps the cooker leveled and prevents spills (if cooking beans, before they have time to soak in the cooking water). On a rounded-surface, the cooker can rock from side to side.

When is the food ready?

Cooking times on a very sunny day resemble those from cooking on a stovetop(or in an oven), without using a pressure cooker. The reason the cooking time is comparable is because the tray can't hold a lot of food, it is sized for two people. A larger diameter tube, which could hold more food, would result in longer cooking times.

A half-cake recipe takes about 30 minutes

A half-baguette recipe takes an hour

A 1/2 cup of pre-soaked black beans takes 1-1h30 hours

Etc...

1 cup of pre-soaked chickpeas was the max quantity for a solar tube with an inner diameter of 5.5cm(17in). The tube can only accommodate half bread or cake recipes(we cook them in two batches one right after the other, see "baking with the sun").

Your nose knows best . In the summer Pino's forward hatch is always open, and because a boat at anchor points in the wind the breeze carries the smell of the cooking food inside. The smell emanating from the bow is a clear indication of whether or not the meal is ready.

We began to rely on our noses instead of looking at the time.

Time doesn't mean much when solar cooking because sun cookers don't put out a constant heat like a traditional oven, the temperature inside the tube changes depending on cloud coverage, or if the boat(and the cooker) move out of alignment for too long.

Obstacles to cooking

Land obstructions . When anchored in bays that are surrounded by tall mountains the sun sets early, cutting down on possible cooking hours. When Pino is stern-tied to a tree, or to a rock face, the boat is still and it's easier to set the cooker, but proximity to shore also means that the land itself will eventually cast a shadow.

When stern-tied in Roscoe Bay the sun fell behind the tree line we were tied to at around 1700 everyday. Boats tied to the opposite side of the bay had more sun in evenings but in the morning would have to wait for the sun to rise above the tree line.

Windy days . On a sunny but blustery day a boat will yaw and swing, causing the cooker to repeatedly go out of alignment with the sun, but the wind direction doesn't change and so the boat always returns to the same position. Swinging at anchor didn't alter the cooking time too much.

We have cooked food on the bow in a near-gale(seebeaufort scale) without any issues, although we liked to place stoppers(shoes, or ropes) at the foot of the cooker. With food in the tray the cooker becomes bottom heavy and won't tip easily, even when the reflectors are near-vertical, but we preferred to add stoppers or to tie short lengths of rope to it just so we wouldn't have to think about it. Evidently, cooking in anything more than a near-gale is a bit foolhardy. It is important to note that the reflectors on our solar cooker are not very large, designs with larger...